Phonograph recording control system



Dec. 14, 1937. E. c. GUEDON PHONOGRAPH RECORDING CONTROL SYSTEM Filed July 51, 1935 2 Sheets-Sheet 1 v 1937. E. c. GUEDON PHONOGRAPH RECORDING CONTROL SYSTEM 2 Sheets-Sheet 2 Filed July 31, 1955 lll Patented Dec. 14, 1937 UNITED STATES PATENT OFFICE TEM Emile C. Guedon, Audubon, N. 3., assignor to Radio Corporation of America, a, corporation of Delaware Application July 31, 1935, Serial No. 34,015

21 Claims.

The present invention relates to a phonograph recording control system for use in connection with electro-magnetic phonograph pickup devices in reproducing sounds from phonograph records and in recording sounds thereon through the medium of electrical currents transmitted to or received from the pickup device.

In recording sounds through an electrical pickup device a heavier stylus pressure is required than in playing back the same record to reproduce the sounds recorded thereon. This is particularly true of the usual home recording system now provided in connection with certain radio phonograph combinations. The application and removal of the recording weight causes a certain amount of inconvenience in operation and in the recording process the application of the recording weight to the pickup device may be forgotten with the result that the recording may be lacking in full tone qualities or may even be of no value.

It has been found that for recording, a pressure on the stylus to give satisfactory results may be in the range from 1 to 2 lbs. For phonograph g5 reproduction, however, the stylus pressure may be from 4 to 6 02s., and for long playing or bookreading records with a fine recording groove the stylus pressure may be much lighter than for regular reproduction and may even be as low 30 as 1 02., although at present the stylus pressure for that purpose is between 2 and 3 ozs. or about one-half that for regular record reproduction.

It is, therefore, a primary object of the present invention to provide an improved means for adjusting the stylus pressure on the record surface and means in conjunction therewith for effecting appropriate circuit connections with the pickup device for operation at the adjusted stylus pressure.

4-3 It is a further object of the present invention to provide improved means for simultaneously adjusting the pressure applied by the stylus on the record surface and circuit connections with the pickup device in predetermined relationship 45 to each other. i

It is an object of the present invention to provide an improved phonograph recording control.

system including means for adjusting the stylus pressure automatically with changes in the pick- 50 up connections in the transition from phonograph operation to recording operation.

It is also an object of the present invention to provide an improved phonograph recording control system wherein the switching operations for 55 changing from a recording operation to phonograph operation is efiected by changes in the stylus pressure adjustment of the phonograph pickup device.

It is a still further object of the present invention to provide an improved phonograph pick- 5 I up control system wherein a movable weight associated with the phonograph pickup suspension means may be moved to a plurality of differing positions to provide a plurality of differing stylus pressures in connection with the record surface 10 and phonograph circuit control switches operable by said weight in certain or all of said diifering positions to provide suitable circuit connections for the proper operation of said pickup device with the adjusted stylus pressure. 15

The invention will, however, be better understood from the following description when considered in connection with the accompanying drawings and its scope will be pointed out in the appended claims. 20

In the drawings Figure 1 is a cross-sectional side view of an electric pickup device and suspension means therefor embodying the invention. Fig. 2 is a plan view of a major portion of the device of Fig. 1 with the cover broken away to show the interior construction. 7

Fig. 3 is a transverse sectional view of the device of Fig. 1 taken on the line 3-3 in the direction of the arrows.

Fig. 4 is a schematic circuit diagram of a radio phonograph system embodying the pickup device of Figs. 1, 2 and 3 showing the switching connections effected thereby, and

Fig. 5' is a side view partly in section of a modification of the invention shown in Figs. 1', 2 and 3 together with a schematic circuit diagram to illustrate the connections for the pickup device. 7

Referring to Figs. 1, 2 and 3 a phonograph pickup device 5 having a stylus 6 is arranged to bear upon a record surface I when supported 40 from a pivot axis 8 provided in a rotary pedestal 9. The pickup device is supported with respect to the pivot axis 8 on a hollow rectangular arm 10 having a removable cover plate ll.

The interior of the arm provides an elongated chamber through which a counterweight l2 is movable longitudinally toward and away from the pickup device and on opposite sides of the pivot axis 8 so that it may overhang the axis 8 to the rear to reduce the stylus pressure or may be moved forward adjacent of the pickup device to increase the stylus pressure.

A further position for the counter-weight is provided substantially directly over the pivot axis 8 where it is neutral in its effect upon the stylus pressure, the overhang of the arm to the rear of the pivot axis being sufiicient to counterbalance the pickup device and provide a predetermined desired stylus pressure on the record surface. I

The cover plate I I is provided with an elongated slot l3 to permit a handle I4 to be attached to the counter-weight I2 to move it to the desired position along the arm and in the present example three definite positions are provided in conjunction with three depending wells in the bottom of the pickup arm as indicated at l5, l6 and H. The wells provide definite locations for the counter-weight and definite stylus pressures dependent upon the relation of the weight of the counter-weight to its discontinuance from the horizontal pivot axis 8. The well I5 is located adjacent to the pickup device 5 to provide a relatively heavy stylus pressure while the well I! is located on the oppositeside of the pivot axis 8 to counter-balance thepickup device and arm thereby to provide a very light stylus pressure on the record surface. 7

The third well l6 is located substantially over the pivot axis 8 and slightly to the rear thereof whereby the counter-balance effect is substantially zero and serves to add a slight counterbalance effect upon the arm and pickup device to'provide a desired normal record playing pressure on the stylus.

The counter-weight is definitely located and positioned against further movement by a spring pressed roller I8 carried on a continuation of the handle l4 and pressed downwardly from within a recess 19 in the counter-weight by a spring 20. The weight is released from the well by pulling upwardly on the handle [4 and then moving the counter-weight through the new position until the roller engages in the well corresponding to the selected position. As shown more particularly in Fig. 3 each well is provided with electrical contact members 2|, 22, 23, 24, 25 and 26 which are arranged to be operated by the roller when it seats in the well. In the present example the contact members are of fiat spring material extending outwardly into the-well from the side thereof and are suitably insulated as indicatedin Fig. 3 by spacing insulating strips 21. Fig. 3 also shows the construction of the horizontal pivot axis 8 and the vertical pivot axis indicated at 28 in the pedestal'a. f I It will be seen that by moving the counterweight to the differing positions shown the switching contacts may be operated and in the present example such contacts are arranged to be closed when they roller is in position in the corresponding well although it is obvious that any other suitable switching arrangement maybe provided. In the construction shown the counterweight is moved to the forward position shown in Figs. 1 and 2' for recording operation to apply a relatively heavy pressure to. the stylus ,and, accordingly, the contacts :23 and 24 may be utilized to effect a, recording connection for the graph pickup device 5.

This position is indicated inFig. 2 by the indicatorsR-R. i

The counter-weight is moved to the intermediate position designated at P inFig. 2 for phonograph operation and closure of the contacts 2|, 22'may be arranged to, effect a phonograph operating connection, for, the pickup device 5 for the reproduction of sounds from records.

In the positionto the rear as indicated atB in Fig. 2 the counterj-weightispositioned for relapho'notively light stylus pressure such as is required in reproducing sounds from book recordings and long playing records where the groove is relatively fine and the walls of the groove are thin. The contacts 25' and 26 may, therefore, be operated to control the pickup device to provide a connection suitable for the reproduction of sounds from such recordings.

The various connections referred to may be provided in any suitable manner whereby the desired connections for the pickup device and the pressure applied to the stylus may be adjusted in predetermined mutual relation to each other for proper operation of the pickup device in the recording and reproduction of sounds from records.

A radio phonograph system wherein the device of Figs. 1, 2 and 3 may be used for recording radio programs and for reproducing records of the normal type and of the fine groove or long playing type is shown in Fig. 4 to which attention is now directed. The circuit of Fig. 4 represents any suitable circuit adapted to be controlled by con-' tacts in conjunction with means for adjusting the stylus pressure and is particularly adapted to open circuit contacts such as shown in the device of Figs. 1, 2 and 3.

Referring to Fig. 4 the contacts 23 and 24, 2i and 22 and 25 and 23 are shown in substantially the same relation to each other as in Figs. 1, 2 and 3 along the tone arm which is indicated by the dotted outline 28' and the counter-weight is indicated at 29. For the sake of simplicity in the diagram other elements of the arm are omitted and the pickup winding is indicated at the forward end of the arm at 30. In the'diagram a radio receiver indicated at 3| is provided with an audio frequency amplifier 32 and a loud speaker device 33. In the normal operation of the receiving system the output of the radio receiver is applied directly through the audio frequency amplifier to the loud speaker device 33 and in the present example such connection is indicated by an output lead 34 through a switch contact 35 to a a switch arm 36 thence through the primary 3'! of an audio frequency input transformer 38 for the amplifier 32 and returning to the radio receiver through ground connections 39.

The output transformer of the amplifier 32 is indicated at 49 and is provided with a secondary winding 4| having a tap 42 thereon for the loud speaker device 33 while the output of the entire secondary winding is taken through a lead for recording purposes in connection with the pickup device 30. The circuit arrangements described indicate the usual connections in a radio receiver for recording purposes and further includes in connection with the switch 36 a contact 45 for phonograph input to the amplifier portion of the receiving system. a

The phoongraph pickup coil 30 is provided with output terminals 46 and 41. The latter-terminal is connected through an insulated output lead 48 V to each of the separate switches and in the present example to the contacts 23, 2| and 25. The terminal 43 of the pickup coil may be grounded to the arm and in the present example is connected to the outer grounded metallic shield for the output lead 48 as indicated by the dotted outline 50 which extends outside the pickup device to a terminal 5| which is connected to one terminal 52 of a volume control potentiometer 53 and grounded as indicated at 54 to the apparatus chassis.

The contacts 22 and 26 are connected to a pickup output lead 55 which extends through the shield 50 to the opposite terminal 56 of the volume control potentiometer device. 53. The'volume control potentiometer is provided with a movable contact 51 which is connected through a 1 lead 58 with the contact 45 of the'radio phonograph switch comprising the contacts 45, 35 and 35 which may be designated generally by the reference numeral 60. The operation'is such that when the switch (it is operated to close the arm 36 with the phonograph input contact 45 signals from the phonograph pickup coil 30 may be transmitted through the output lead 48 and either of the contacts 22 or 26 from the contact 2| or 25 thence through the output lead 55 to the potentiometer device at the terminal 56 thence through the resistor 53 and returning through the terminal 5| and the grounded shield 59 through the pickup coil.

The transformer 38 is connected through the ground 39 with the ground 54 and the signal potentials set up across the volume control resistor 53 may be taken in whole or part according to adjustment of the contact 5'! to apply the phonegraph pickup signals to the primary 3'! of the transformer through the switch 60.

Operation of the counter-weight 29 serves to close the selected contacts and in the present example it is shown in position for normal record playing wherein the contacts 2| and 22 are closed. The weight may also be moved to close the contacts 25 and 26 for long playing records or book reading wherein the operation is the same but with added counter-weight effect on the tone arm as hereinbefore pointed out.

When the switch $0 is moved to connect the arm 35 with the radio input terminal 35 radio signals transmitted through the lead 34 and ground are applied to the transformer 33 in the same manner as phonograph signals and are amplified and reproduced through the loud speaker 33.

With the switch 3!] in the radio position signals may also be recorded by connecting the pickup coil 30 to the output lead 44 and this is arranged by connecting the output lead 44 to the contact 2 of the switch adjacent to the pickup. This switch comprising the contacts 23 and 24 is closed when the counter-weight is moved to the forward position to apply a heavy weight to the pickup device and to the stylus. In this manner the pickup device is automatically connected to the output of the receiver to receive the signals therefrom for recording purposes and at the same time the proper weight is applied toproduce a desired heavy stylus pressure. In this position the other switches are automatically opened to disconnect the volume control device from the pickup circuit.

From the foregoing descriptionit will beseen that with a system as shown and described the proper predetermined connections for the pickup device and the proper stylus pressure are automatically provided in predetermined relation to each other so that the proper operation of the system is assured at all times. arrangement is particularly desirable in radio phonograph combination apparatus for home use where the operation may be in the hands of those not particularly skilled and non-technically inclined and also prevents in any case the recording operation without the applicationoi the recording weight. Furthermore the'r'ecording weight being slidably mounted within the tone arm pro vides a compact construction of pleasing appearance and prevents the weight from becoming detached and lost.

Adjustment of the stylus pressure may be efiected by means other than a movable weight. For example, it may be adjusted by means of variable spring pressure applied to the pickup device in a suitable manner and means maybe provided ior'automatically operating a switching mechanism for controlling the pickup circuit connections in predetermined relation to the stylus pressure adjustment. Such an arrangement is shown by way of example in Figure 5 to which attention is now directed.

Referring to Fig. 5 an elongated pickup device 5! having a pickup coil 62 and a stylus 63 in contact with a record surface 6 3 is pivotally mounted on a horizontal pivot axis 65 to move verticallywith respect to the record surface on the outer end of a goose neck power arm 66 having a rearwardly extending base portion 61 provided with a vertical hollow shaft 68 journaled at its upper and lower ends in a fixed bearing frame 69. The upper and lower bearing members are resiliently mounted as indicated at 10k and H and the pickup output leads indicated at 12 are taken through a cable 13 to an insulated control switch M through the hollow shaft 68.

The switches arranged for controlling phonograph operation and recording operation of the pickup device and the stylus pressure and operation of the switch are controlled by a suitable operating handle or lever 15 mounted on the tone arm 56 in an opening 16 therein.

Theinner end of the lever .is .pivotallyeonnee-ted at ii to a ring member 1-8 which in turn is connected to a pivoted hook 19 carried by the arm and arranged to engage at its outerend with a projecting rear end 8! of the pickup device to operate an upward pressure thereon which transmitted through the pivot axis 65 results in' an increased downward pressure on the stylus 63;

A predetermined desired pressure is applied .in this manner by a tension spring 82 connected with a stud 83 mounted on the arm 65 and connected with the hook 19 to move its' lower end BE! in the direction of the pickup end 8!.

In the present example the operating lever '15 and the connecting link 18 are arranged in such a manner that the pivoted connection 'll moves over dead center to the position shown so that the spring tension exerted by the spring 82 serves to hold the link .and lever in the position as shown in the drawings wherein the pickup device is under normal pressure created by its weight counter-balanced by the rearward extension 8i about the pivot axis 65 for normal record playing operation. A flexible wire connection comprising a steel wire 84 carried by a flexible guide tube 85 within the tone arm is connected at its inner end as shown to thepivot point 1'? and at its opposite end extends below the mounting board indicated by the dot and dash lines 85 for connection with an operating nected to the terminal and the farm- 81 with the terminal 9| and a lead 93 to the amplifier input to supply phonograph record signals there'- to. The other pickup lead 94 is connected to ground thereby completing the circuit to any suitable amplifier such as that shown in Fig. 4. For example, the lead 92 may correspond to the lead 48 in Fig. 4 and the lead 93 may correspond to the lead 55 in Fig. 4.

Whenthe control lever 15 is moved forward, that is the left as viewed in the drawings the link connection serves to move the end 80 of the hook 19 against the rear 8| of the pickup device and the retracting action of the spring 82 is sufificient to exert a pressure through the hook 19 to cause the stylus 63 to acquire a predetermined desired pressure on the record surface for recording purposes. At the same time the connection wire 84 is released to permit the arm 8'! of the switch 74 tomove downwardly and to force it into contact with a second insulated contact 95 having a terminal 96 which is connected with a lead 91 from an amplifier output circuit, the lead 91 corresponding to the lead 44 in Figure 4. This arrangement serves to connect the pickup device-to the amplifier output for recording purposes automatically in response to adjustment of the stylus pressure. This arrangement for simultaneous control of stylus pressure and circuit connections in'an electric pickup or phonograph recording system is otherwise the same as described in connection with Figure 4. The advantage of the construction shown in Figure lies in the fact that the arm may be of any suitable shape since it does not carry a movable weight and the stylus pressure is controlled by applying spring pressure to the pickup device. It is also obvious that any suitable switching arrangement may be provided in connection with the means controlling the stylus pressure for effecting other connections in a recording system to adapt the pickup device for receiving amplified signals to be recorded or to transmit signals generated by operation in contact with a record groove;

I claim:

1. The combination with an electric pickup device for recording and reproducing phonograph records and the like, of means for adjusting the stylus pressure thereof on a record surface and means for changing electrical connections therewith in predetermined relation to the adjustment of said stylus pressure.

2. The combination with an electric pickup device, of means for simultaneously adjusting the stylus pressure of said device and eifecting predetermined electrical connections therewith whereby said pressure and each of said connections are coordinated to provide predetermine recording and reproducing operations.

.3. In a phonograph recording control system, the combination with an electric pickup device having an operating winding for the generation and reception of signal currents 'and'an operating stylus for engagement with a record groove,

of means for applying diifering degrees of pressure on said stylus, and switching means actu ated by operation of said means for controlling electrical connections with saidwinding whereby said device is adjustable for recording and reproducing signals in connection with a record surface.

4. The combination with a radio receiver and an audio frequency amplifier therefor, of a phonograph pickup device adapted to record and reproduce signals in connection with a phonograph record surface, saidamplifierhaving an input circuit and an output circuit, means for selectively connecting said pickup device with either one of said circuits, and means for simultaneously adjusting the stylus pressure of said pickup device on a record surface and actuating said and reproducing connections and predetermined stylus pressures therefor in predetermined relationship to each other.

5. The combination with an audio frequency amplifier, of an electric phonograph pickup device, means providing a connection for applying signals from said pickup device to said amplifier, means providing a connection for applying signals from said amplifier to said pickup device, and means for automatically operating said first and second named means in response to adjust ment of the stylus pressure of said pickup device on a record surface.

6. The combination with an electric pickup lselective connection means to provide recording device and pivotally mounted suspension arm therefor, of a counter-weight for the pickup device movable along said arm to predetermined positions to adjust the stylus pressure of said pickup device and switching means for said device associated with said movable counter-weight to be actuated thereby when in at least one of said predetermined positions.

7. The combination with an electric pickup device, of a. pivotally mounted suspension arm therefor, a counter-weight for the pickup device for adjusting the stylus pressure thereof movable along said arm to positions adjacent to said device and in spaced relation thereto on opposite sides of the pivotal connection of the arm, and switching means for said pickup devicepositioned along said arm to be actuated by movement of said counter-weight thereby automati-j cally to control the electrical connections with said pickup device. v

8. A pickup device in accordance with claim 7, further characterized by the fact that the pickup arm provides an elongated housing for the counter-weight and is provided with a series of wells along the housing for said switching means, and that the counter-weight is provided with a 7 spring pressed roller adapted to enter said wells to actuate said switching means. 7

pension arm, a phonograph pickup device mounted thereon, means carried by the arm for applying additional pressure to the pickup device in the. direction of a record'surface, and selective switching means connected with said last named means to be actuated thereby for controlling circuit connections with said pickup device.

11. In combination, a, phonograph pickup suspension arm, a phonograph pickup device mounted thereon, means carried by the arm for applying additional pressure to the pickup. device in the direction of a record surface, selective switching means connected with said last named means to be actuated thereby for controlling circuit connections with said pickup device, said first named means comprising a lever, a spring for applying pressure to said pickup device, means actuated by the spring for engaging said pickup device, I

releasing the spring pressure.

12. The combination with an electric pickup device, of a pivotally mounted suspension arm. therefor, a counter-weight for the pick-up device for adjusting the stylus pressure thereof movable along said arm to positions adjacent to said device and in spaced relation thereto on opposite sides of the pivot connection of the arm, switching means for said pick-up device positioned along said arm to be actuated by movement of said counter-weight to said first named positions, and means providing electrical circuit connections with said pick-up device through said switching means, whereby said connections are automatically controllable in accordance with the position of said counter-weight and the adjusted stylus pressure.

13. In combination, a phonograph pick-up device, suspension means therefor providing a pivot axis of movement for said device with respect to a record surface, means providing pressure for applying said device by movement about said axis to said record surface, means carried by said suspension means and connected with said last named means for controlling said pressure, electrical circuit controlling means associated with said pick-up device, and common means for operating said pressure and circuit controlling means to provide pressure and circuit changes in predetermined mutual relationship to each other.

14. In electric phonograph apparatus, a unitary tone-arm and switch structure comprising a hollow tone-arm, and switch means mounted within said tone-arm to connect said apparatus for sound recording or for sound reproduction whereby space within said tone-arm. is utilized for housing said switch means and whereby said switch means is electrically shielded.

15. In electric phonograph apparatus, a combined tone-arm and switch unitary structure comprising a hollow tone-arm, switch means mounted within said tone-arm to connect said apparatus for sound recording or for sound reproduction whereby space within said tone-arm otherwise wasted is utilized for housing said switch means and whereby said switch means is electrically shielded, and means mounted on said tone-arm for manually controlling said switch means.

16. In electric phonograph apparatus adapted to record sound on records and to reproduce sound from records and comprising a sound-box, an amplifier and a loud speaker, a hollow tone-arm, and switch means associated with said soundbox, amplifier and loud speaker to connect said apparatus for sound recording or for sound reproduction, said switch means being mounted within said hollow tone-arm whereby space within said tone-arm otherwise wasted is utilized for housing said switch means and whereby said switch means is electrically shielded.

17. In electric phonograph apparatus adapted to record sounds on records and to repoduce sounds from' records and comprising a. soundbox, a tone-arm, switch means mounted within said tone-arm to connect said apparatus for sound recording or for sound reproduction, means 7 to load said sound box, and means for simultaneously connecting said apparatus for sound recording and for loadingsaid sound-box, and for simultaneously connecting said apparatus for sound reproducing and for removing the loading space within said tone-arm is utilized for housing said switch means and whereby said switch means is electrically shielded.

19. In electric phonograph apparatus, means providing a combined tone-arm and switch unitary structure capable of being readily connected to phonograph apparatus arranged only for sound reproduction, for converting said second-named phonograph apparatus to apparatus adapted both to sound reproduction and sound'recording, said means comprising a tonearm having switch means mounted therewithin to connect said last-named apparatus for sound recording or for sound reproduction whereby space within said tone-arm is utilized for housing said switch means and whereby said switch means is electrically shielded, and means mounted on said tone-arm for manually controlling said switch means.

20. In electric phonograph apparatus, a hollow tone-arm, and switch means mounted within said tone-arm to connect said apparatus for sound recording or for sound reproduction, said switch means being electrically shielded by said tonearm.

21. In electric phonograph apparatus, a hollow tone-arm, switch means mounted within said tone-arm to connect said apparatus for sound recording or for sound reproduction, said switch means being electrically shielded by said tonearm, and means mounted on said tone-arm for manually controlling said switch means.

EMILE C. GUEDON. 

